The officers were conducting a search at a home in the East Bay city of Dublin when the shooting occurred just after 1 p.m. BART Police Chief Kenton Rainey said the officers were following up on a crime that was committed on BART property.

The officer who was shot was transported to a local hospital, where he died from his injuries.

"The entire BART organization is deeply saddened by this tragic event, and we ask the public to keep the officer's family in its thoughts and prayers," Rainey and BART General Manager Grace Crunican said in a joint statement.

They added the officers' identity and other details are being withheld at this time.

Rainey noted the killing was the first death of an officer in the line of duty in the BART Police Department's history. Both Rainey and Crunican have visited with the deceased officer's family to provide condolences and offer support.

The Dublin Police Department, which contracts with the Alameda County Sheriff's Department, has taken over the investigation.